In vehicles, including trailers, which utilize air ride suspensions, a trailing arm beam is provided on each side of the vehicle to pivotally connect a vehicle axle to the vehicle frame. A conventional trailing arm beam is of U-shape transverse cross section usually bent or otherwise formed from a piece or several pieces of metal. The forward end of each trailing arm beam is conventionally attached to a resilient bushing mounted on a hanger depending from one side of the vehicle frame. The rearward end of each trailing arm beam supports an air bag or air spring which is positioned between the trailing arm beam and the vehicle frame. The vehicle axle is attached to either the top or under side of each trailing arm beam depending upon whether the axle is attached to the vehicle in what is called an overslung fashion or is attached in what is called an underslung fashion. In either of these manners of attachment, the vehicle axle is welded to each trailing arm beam, either directly or indirectly, forming a rigid connection between the axle and each trailing arm beam. Dynamic and static stresses caused by the vehicle load are exerted on the trailing arm beams while the vehicle travels over a road. These stresses may be concentrated at the welds connecting the trailing arm beams to the axle. In such connections, it is desirable to reduce the stress load per linear unit of weld forming the connections between the trailing arm beams and the vehicle axle and to transfer the stress from the welds to the resilient bushings and the air springs.
The present invention is directed to an axle suspension system for a wheeled vehicle which more efficiently transfers stresses from a vehicle axle through trailing arm beams to resilient bushings and air springs supporting the trailing arm beams. A purpose of this invention is to reduce the stress applied per linear unit of weld between the vehicle axle and the trailing arm beams. To obtain this result, the invention utilizes an axle cradle which extends laterally beyond the sides of each trailing arm beam. To further dissipate the stresses, sponsons are attached to each trailing arm beam on opposite sides thereof to provide to additional support to the axle cradle and thus to dissipate the stresses being transferred from the axle cradle over a greater expanse of the trailing arm beams.
Another aspect of the present invention is to more efficiently transfer dynamic and static stresses from the vehicle axle to the resilient bushings supporting the trailing arm beams and to reduce the stresses applied to the air springs. This is accomplished by providing a closure wall for a portion of the normally open side of each of the U-shaped trailing arm beams which closure walls each extends from the resilient bushing of its trailing arm beam to the axle cradle. To assist in this transfer of stresses, a gusset is mounted on the closure wall of each trailing arm beam in engagement with the axle cradle.